SEXUAL DIMORPHISM OF SODIUM-SENSITIVE RENAL-WRAP HYPERTENSION

One-kidney, figure-8 renal wrap or sham operation was performed on mal e and female rats to determine if a difference existed in the expressi on of hypertension between the sexes. Animals were prepared with radio telemetry transmitters to monitor mean arterial pressure and heart rat e continuously throughout an 8-week study. Dietary sodium content was changed during the post-renal-wrap period from normal (100 mu mol/g ch ow) to high (2000 mu mol/g chow) to low (<2 mu mol/g chow) to assess s odium sensitivity. Both male and female rats experienced an increase i n arterial pressure after the renal-wrap procedure; however, the hyper tension was significantly attenuated in the females. High salt caused a further increase in both groups of rats that was again attenuated in the female rats. Low sodium diet reduced arterial pressure in all gro ups of rats. Heart rate was significantly elevated in the female rats during all dietary interventions. The data were fit to a cosine functi on to analyze circadian rhythm changes. An increase in the light/dark difference for arterial pressure in the hypertensive rats during high salt diet resulted in an increase in the circadian amplitude (range of the rhythm). In the normotensive rats fed a high salt diet, the arter ial pressure acrophase (peak of rhythm) was delayed while the heart ra te acrophase was shifted to an earlier time. These studies showed that female rats are protected against one-kidney, figure-8 renal-wrap hyp ertension and are less sensitive to the effects of sodium.